Invoices not showing in Projects

Invoices not showing in Projects

In our ZohoInvoice account we bill for three country offices in four currencies. In order to maintain separate currencies we create an additional customer for invoicing rather than use the one in CRM (our CRM default currency is USD and our Invoice base currency is AED). For example, ABC Co. in listed in our CRM but in Invoice it needs to be ABC Co. INVOICE in order to invoice in Saudi Riyals rather than either USD or AED. 

This works however, I can't seem figure out how to link the invoices with the Projects since I want the project to still display within the CRM record for the real company rather than the dummy CRM entry I had to create for invoicing purposes. 

Make sense? 

Can I link the "ABC Co. INVOICE" entry with the real "ABC Co." in my CRM so that the invoices actually display in projects and in the CRM listing for the company. 

Is Member Account the way to accomplish this? Other suggestions?

Thanks